The onion, from the allium cepa family, is a vegetable with many health benefits as well as a very versatile food for the kitchen. Let’s find out in this guide, how are onions stored?
Although onions, together with garlic and potatoes, are one of the foods that last the longest, we can find ourselves with the problem of, if we have a large harvest, how to preserve them. There are different methods for preserving onions both at home and at an industrial level. Next, we are going to give you the keys to preserve and store onions in good condition.
How are onions stored?
First of all, end-of-season onions must be stored, since those harvested in spring and summer do not last as long and must be consumed within a few weeks after harvest. The ideal is to store the onions that are harvested in the fall since they last all winter.
The variety of onions is also important, for example, hot onions contain sulfur (which makes you cry) and helps preserve the onion in winter.
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Home storage:
When choosing the right place to store onions, it is very important not to place them near potatoes as they would absorb their moisture and spoil them.
- Do not use plastic bags to store them.
- Find a dark place so they don’t spoil.
- Choose a place that is at a constant temperature between 4ºC and 10ºC.
- The storage space must be well ventilated and dry.
- You can get the onions ventilated properly by using a mesh or netting and making a knot between each onion to prevent them from absorbing moisture on contact.
- Another option is to use a paper bag with small holes and fill it halfway with onions to circulate the air.
Industrial storage:
For the correct storage of the onion, it must meet the following requirements:
- The variety of onions must be suitable for storage, as mentioned above.
- It must have been harvested when fully ripe.
- The bulb must be firm and compact.
- The bulb must have low water content.
- The skin must be strong.
- It should not be fertilized with nitrogen during the last 6 weeks of cultivation.
- Sufficient amounts of lime must have been applied.
However, the onion requires several operations before storage, one of the main ones is drying.
The goal of drying is to remove all surface moisture from the outer layers, thus sealing the onion and stem. This process is intended to dehydrate the outermost layers.
The suitable temperature to carry out the drying oscillates between 25 to 30ºC.
The storage will be carried out in cold storages suitable for the conservation of onions. The onions will be stored in wooden boxes. Its location in the cold storage will be carried out in such a way as to allow good air circulation from both the evaporators and the support fans, not exceeding the maximum storage level.
Its storage will be carried out at a constant temperature and humidity, avoiding fluctuations, and in complete darkness, it must be taken into account that the bulb is still alive.
Industrial conservation:
For industrial conservation, it is necessary to delve a little deeper. Proper cold storage allows us to extend the shelf life of onions:
- Use the thick neck bulbs first as they are the oldest and don’t last as long as the smaller ones.
- Periodically inspect the cold storage where the onions are kept and discard any that start to rot.
- The temperature must be adequate so that the onion does not rot, being able to reach 1 ºC and the humidity must be kept between 65 and 75%.
- Likewise, the correct distribution of air inside the chamber must be taken into account for better homogeneity.
- The changes in temperature of the onion must be slow, ensuring that both the heart and the outer layers have the same temperature. With sudden temperature changes, the cells of the bulb can be destroyed. We recommend heating a maximum of 2ºC per day, depending on the different factors (temperature, humidity, etc.)
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